Introduction
This guide was inspired by getting a DD on one of my snow flake photos. It partially got a DD because it included details about how it was taken, though not all that much. A lot of people seemed interested, so I thought I could write some more. This is as much of a guide as I could make, given that I've only taken snow flake pictures in one way; the rest is just various little things I've learned by doing it, and a bit of speculation here and there. I've tried to be very detailed, because although I'm sure lots of you will find a lot of the details obvious, I think some people may not - different people know different things.
Questions, comments, criticisms, etc. are very welcome!
Equipment
Camera + Lens
To fill the frame significantly with a snow flake, you'll need macro capability significantly better than 1:1 (feel free to skip this part if you already have that). Theoretically this would be possible with a compact camera, but probably not without custom made add-ons, so I'm going to assume you're using an SLR for this. There are various ways to achieve better than 1:1 macro on an SLR. I do it with a +5 close-up lens (aka diopter; it screws on the front like a filter) on my 100mm 1:1 macro lens. But there are many other ways to do it. One way I know will yield slightly better macro than I have, is a reversed 28mm lens. Other methods include different combinations of:
extension tubes,
bellows,
teleconverters,
close-up lenses, and
reversing rings.
It's hard to say exactly what ratio you're going to end up with without trying. Reversing rings work better the more wide angle the lens is, while everything else works better on a more telephoto lens. Probably the cheapest way to go is with a reversing ring, but only if you have a wide angle lens. My setup is somewhat expensive (100mm 1:1 macro lenses are usually at least $400 new; I got mine for $300 used), and you do have to be wary of the quality of close-up lenses, since they are another optical element (mine was custom made from a Canon lens element; I don't know how much a good one would cost normally). But the nice thing about it is that the lens is normally connected to the camera. With the other options, it goes through some other connection first, and unless you get an expensive one, you'll lose most or all camera/lens functionality. Which means setting the aperture manually with the aperture ring (if your lens doesn't have one it won't work at all), and not having the aperture wide open while you focus and frame the picture. I've done this before with extension tubes, and it works, but it is incredibly inconvenient.
Tripod
You will most definitely need a tripod, with such precise focusing, and relatively long exposure times. Any tripod should work, but ideally you want one that can be easily adjusted by very small amounts.
Backgrounds
Intro
There are an infinite number of possible backgrounds; the following are what I've tried or thought of so far, but I'm sure there are many other things that would work just as well or better. The background is very important with snow flakes, since they're semi-transparent. Even if you manage to fill most of the frame with the snow flake, you'll still see the background a lot, through it.
Hairy cloth
This is an ideal backgrounds in my opinion. So far my best pictures have been on a mohair scarf, and wool mitts/gloves. The hairs provide an interesting background, while at the same time suspending the flakes nicely to have their picture taken. It's also supposed to be chaotic, so looking at it closely doesn't reveal any “flaws”. And of course, it's really easy to get ahold of, in all kinds of shapes and sizes.
Feathers
These have many of the advantages of hairy cloth, but they're harder to use since they're small, not a uniform shape, and can easily blow away. I think they could make a very nice background though, if you can pull it off. Unfortunately, the only time I've tried it so far (with a peacock feather), it was windy, not enough snow, and not big enough snow, so it was impossible to get anything really good.
Glass
At first I thought glass would be perfect - you could get an isolated snow flake with an abstract solid-color or gradient background, just by putting anything colorful a short distance behind the glass. But once I tried it, I came to the conclusion that doing that well would require a much more sophisticated setup than I have. When looking that closely at it, it's very easy to notice any dust, scratches in the glass, and melted snow (though the latter could be avoided by pre-chilling the glass). I got some pretty good flakes, in focus and sharp, but the pictures weren't very good, as they suffered from all 3 of these things, as well as not very good backgrounds. I may try glass again eventually, but I think it's safe to say it's harder to do well than the fibrous options.
Weather and flakes
Most of the time when it's snowing the flakes are not big enough and/or aren't symmetrical and nice enough. I find (and I think I read somewhere) that the best flakes occur at around -5ºC. This doesn't mean there are always good flakes when it's -5ºC, because it depends on the temperature up in the clouds, and also the humidity level - but if it isn't within 2-3 degrees of -5ºC, it probably isn't even worth checking how good they are. Since it's relatively rare to have good flakes, you'll probably want to have everything ready for when they do come, and watch the temperature (and forecast) so you don't miss it - especially if you're using natural light, and you're in one of the many places where it only snows in the time of year with the shortest days.
Setup
I have a rather sketchy setup that could surely be improved upon. I've got a piece of plywood (approximately 3 x 2 feet) resting on a chopping block (a 1 foot tall stump), half sheltered by the wood shed (or out in the open, depending how heavily it's snowing). On top of that, there's a piece of firewood on its side. I put whatever background I'm using on the piece of firewood to have it on an angle, and alternate backgrounds on the plywood to collect snow, along with anything else I might want easily handy. The tripod goes in front of that, at its lowest height. This can result in formal complaint letters from your back and legs for all the crouching if you're out for a long time, but it's a lot more stable than if it were higher, and easier to make tiny adjustments to focus.
Taking the pictures
Collecting flakes
Most of the time you can just put your backgrounds where you want them, and let them get covered in snow. I usually do it this way, and every once in a while shake all the snow off, so the background is still whatever I've chosen, and not other snow. One thing I've found is that you can actually move the flakes around a bit, by shaking what they're on. It doesn't always work, and sometimes they break, but it works better than I expected. One time it mostly stopped snowing and I wanted to keep taking pictures, but on a new background, and it actually worked to shake the flakes off a mitt where there were lots, onto the new glove.
Focusing
It's best to line up the camera directly with the flake so it can be completely in focus, and I think it's best to try to have the focus point be the center of the (main) flake. The actual focusing is done mainly by doing everything BUT changing the lens' focus distance, since you want it to be at closest focus to get the highest magnification ratio you can (my lens is manual focus, but if yours is auto I'd recommend switching to manual). Instead, move the subject, move the tripod, or adjust the tilt and/or leg length/position of the tripod. I've noticed that with my setup, once the aperture is stopped down, nothing closer than the focus point is ever more in focus, only further away. And in fact, the focus point itself seems to change. This is rather annoying, since the focusing is very precise already. I recommend using the aperture preview to check what's really going to be in focus.
Since moving the tripod such a small amount can be very hard (especially when you start to create ruts in the snow), if you've got it ALMOST there, you could do a small amount of normal focusing - just don't forget to change it back to closest after. Something very strange seems to happen when I do this on my setup though: when I focus further away, it seems to focus closer instead, but I get a lower magnification ratio anyway.
Camera settings
The aperture should be in the range of f8 - f16. Lower than f8, and nothing will really be in focus, higher than f16 and you'll run into diffraction. Diffraction may start to come in at f11 or so, depending the lens, but it shouldn't be too bad up to f16, and will probably be worth the extra depth of field at least up to f13. How long a shutterspeed you can get away with depends mostly on how much wind there is; if you've got a good shelter, of course, you can use whatever speed you need to match the aperture you want. With my minimal shelter, I've usually gotten away with 0.3 to 2 seconds, without noticeable motion blur. Sometimes higher, but that's pushing it. Often, once I've got a picture focused I'll try it with a bunch of different settings, and sometimes a few times with the same setting if I think the shutterspeed is iffy. Using the 2 second timer is always a good idea to reduce camera shake. I always set ISO at its minimum for the best quality; in my case that's 100.
Technical details
Macro magnification
I thought it might be interesting to some, to know the actual size of the flakes, and macro magnification of what I have, so you can tell if you've got a comparable setup, and tell if your flakes are big enough before you get a feel for it. I was also pretty curious myself. I did the calculations by taking a picture of a ruler, and it turns out my setup is approximately 2.74:1 magnification, on my camera's APS-C (2/3 of 35mm) sensor. Which makes size of the area that's in focus 1.42 x 0.94 cm.
Snow flake sizes
The average size of a good flake (for my setup), is about 0.45 cm. The biggest one I've taken a picture of so far was 0.66 cm. My favorite one so far, which got a Daily Deviation, was 0.56 cm. One of the smallest ones I've deemed worthy of taking a picture of, with a normal background, was 0.34 cm. And I've got one that I'm happy with that is only 0.18 cm, because it's got an especially nice background. These measurements are based on how big the longest side of a square that fits the whole flake is; maybe not the most accurate, but by far the easiest, and not terribly inaccurate either.
Other flakey pictures I've submitted
Sta.sh
from *
There can be photography and literature!
Link your art to me so I can put it in an folder for the contest
The deadline is November 17, 2011
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I accept new AND OLD art!
Only ONE entry per person
First place:
a journal feature from ~museoda-arts
Full detailed pic of your choice from ~museoda-arts
let it snow 
AGHHGHJdfgd so pretty.
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